Green modification technology: acylation-glycosylation co-modification of walnut protein and its application in the stabilized encapsulation of lutein

To enhance the poor functional characteristics and low utilization of walnut protein isolate (WNPI), this study treated WNPI with succinic anhydride (SA) and xanthan gum (XG), analyzing the structure and functionality of acylated-glycosylated WNPI (WNPI-SA-XG). Furthermore, a dual-modified protein (DMP) with excellent gelation and emulsifying properties, prepared by adding 0.6 % XG, was selected to modify liposomes (LIP) encapsulating lutein (LUT). The protective effect of DMP-modified LIP on the stability of LUT was investigated. The results indicated that combined modification could unfold the protein structure, enhance intermolecular electrostatic repulsion to reduce molecular aggregation, improve protein flexibility, and thereby enhance its functional characteristics. Specifically, it increased the viscosity and network structure of WNPI. The water-holding capacity and oil-holding capacity of the protein increased by approximately 5.3 times and 1.6 times, respectively. Its emulsifying property and emulsion stability improved by 15.25 % and 11.13 %, respectively, and the thermal denaturation temperature rose by 19.34 °C. DMP modification elevated the encapsulation efficiency of lutein-loaded liposomes (LUT-LIP), enhanced the antioxidant activity of LUT (with DPPH scavenging rate and ABTS scavenging rate increasing by 1.40 times and 3.80 times, respectively), and improved its storage and environmental stability (the retention rate after 30 days of storage at 25 °C was 7.17 times that of LUT-LIP) as well as gastrointestinal digestive stability (with a 24.68 % reduction in release during the gastric phase). This study offered a theoretical basis and technical support for applying modified WNPI and proposed a feasible strategy for utilizing double modified protein-lutein-liposome (DMP-LUT-LIP) as an efficient nutraceutical delivery system.